After installation of the Symantec Endpoint Protection Manager, you might encounter the home page, reports and policy page cannot be viewed. "The website declined to show this webpage".
There are a few things to go through.
1. ODBC connection test.
Login on console and test the ODBC connection to the database.
2. Go to Local security policy (secpol.msc) or Default Domain Policy for domain controller. Under User Rights, add Network service to "Adjust Memory Quotas for a Process" and "Replace a Process level token".
3. Restart IIS. This should fix it.
Contary to other posts on the Symantec forum, there is no need to change the DefaultAppPool identity from Network service to Local System. I have tested this on a domain controller.